Superabsorbent hydrophilic isocyanate-based foam and process for production thereof

Abstract

A foamed isocyanate-based polymer having a cellular structure and containing a superabsorbent material, the polymer being capable of: (i) absorbing at least about 20 times its weight of an aqueous fluid maintained at a temperature of from about 20 DEG to about 25 DEG C., and (ii) retaining at least about 20 times its weight of absorbed aqueous fluid which is bound to the superabsorbent material. A process for producing a foamed isocyanate-based polymer comprising the steps of: providing a substantially uniform mixture comprising an isocyanate, an active hydrogen-containing compound and a superabsorbent material, the superabsorbent material being capable of absorbing at least about 20 times its weight of an aqueous fluid maintained at a temperature in the range of from about 20 DEG to about 25 DEG C.; adding to the substantially uniform mixture an aqueous blowing agent and a catalyst to form a reaction mixture; and expanding the reaction mixture to produce the foamed isocyanate-based polymer; wherein the active hydrogen-containing compound comprises from about 10% to 100% by weight of a hydrophilic active hydrogen-containing compound and from 0 to about 90% by weight a non-hydrophilic active hydrogen-containing compound. The foamed isocyanate-based polymer is ideally suitable for use in an absorption layer in a personal hygiene device.

What is claimed is: 
     
       1. A foamed isocyanate-based polymer having a cellular structure and containing a superabsorbent material, the polymer being capable of: (i) absorbing at least about 20 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining at least about 20 times its weight of absorbed water which is bound to the superabsorbent material, the foamed isocyanate-based polymer being based on an active hydrogen-containing compound having an overall ethylene oxide content in the range of from about 20 to about 70 percent by weight. 
     
     
       2. The foamed isocyanate-based polymer defined in claim 1, wherein the polymer is capable of: (i) absorbing from about 20 to about 100 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 20 to about 90 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       3. The foamed isocyanate-based polymer defined in claim 1, wherein the polymer is capable of: (i) absorbing from about 20 to about 80 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 20 to about 70 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       4. The foamed isocyanate-based polymer defined in claim 1, wherein the polymer is capable of: (i) absorbing from about 35 to about 65 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 30 to about 55 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       5. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is a synthetic polymer. 
     
     
       6. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is a cellulosic polymer. 
     
     
       7. The foamed isocyanate-based polymer defined in claim 6, wherein the cellulosic polymer is a carboxymethyl cellulose. 
     
     
       8. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is selected from a polymer of an acrylic monomer and a polymer of a vinyl monomer. 
     
     
       9. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is selected from the group consisting of polyvinylpyrrolidone, sulfonated polystyrene, polysulfethyl acrylate, poly(2-hydroxyethylacrylate), polyacrylamide, polyacrylic acid, poly(acrylic acid alkali metal salt), starch modified polyacrylic acid, poly(starch modified acrylic acid alkali metal salt), hydrolyzed polyacrylonitrile, poly(hydrolyzed polyacrylonitrile alkali metal salt) and mixtures thereof. 
     
     
       10. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is present in an amount up to about 150 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       11. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is present in the range of from about 20 to about 80 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       12. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is present in the range of from about 35 to about 75 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       13. The foamed isocyanate-based polymer defined in claim 1, wherein the superabsorbent material is present in the range of from about 55 to about 65 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       14. A polyurethane foam comprising poly(acrylic acid alkali metal salt) in an amount in the range of from about 55 to about 65 parts by weight per hundred parts by weight of polyol used to produce the foam, the foam being capable of: (i) absorbing from about 35 to about 65 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 30 to about 55 times its weight of absorbed water which is bound to the poly(acrylic acid alkali metal salt), the foam being expanded from a reaction mixture comprising an isocyanate and an active hydrogen-containing compound comprising a polyol having an overall ethylene oxide content in the range of from about 20 to about 70 percent by weight. 
     
     
       15. A process for producing a foamed isocyanate-based polymer comprising the steps of: providing a uniform mixture comprising an isocyanate, an active hydrogen-containing compound and a superabsorbent material, the superabsorbent material being capable of absorbing at least about 20 times its weight of an aqueous fluid maintained at a temperature in the range of from about 20° C. to about 25° C.;   adding to the uniform mixture an aqueous blowing agent and a catalyst to form a reaction mixture; and   expanding the reaction mixture to produce the foamed isocyanate-based polymer;   wherein the active hydrogen-containing compound has an overall ethylene oxide content in the range of from about 20 to about 70 percent by weight.   
     
     
       16. The process defined in claim 15, wherein the active hydrogen-containing compound comprises an overall ethylene oxide content in the range of from about 35 to about 70 percent by weight. 
     
     
       17. The process defined in claim 15, wherein the active hydrogen-containing compound comprises an overall ethylene oxide content in the range of from about 50 to about 65 percent by weight. 
     
     
       18. The process defined in claim 15, wherein the active hydrogen-containing compound comprises a mixture of at least two active hydrogen-containing compounds, the mixture having the overall ethylene oxide content. 
     
     
       19. The process defined in claim 15, wherein the active hydrogen-containing compound is a mixture comprising an hydrophilic polyol and a non-hydrophilic polyol. 
     
     
       20. The process defined in claim 19, wherein the hydrophilic polyol is selected from the group consisting of diols, triols and tetrols, the hydrophilic polyol containing polyoxyalkylene groups, the polyoxyalkylene groups comprising at least 25 percent by weight of ethylene oxide. 
     
     
       21. The process defined in claim 19, wherein the non-hydrophilic active hydrogen-containing compound is selected from the group consisting of non-hydrophilic polyols, polyamines, polyamides, polyimines, polyolamines and mixtures-thereof. 
     
     
       22. The process defined in claim 19, wherein the non-hydrophilic active-hydrogen-containing compound is a non-hydrophilic polyol selected from the group consisting of polyether, polyesters, polycarbonate, polydiene, polycaprolactone and mixtures thereof. 
     
     
       23. The process defined in claim 22, wherein the non-hydrophilic polyol is selected from the group consisting of adipic acid-ethylene glycol polyester, poly(butylene glycol), poly(propylene glycol), hydroxyl-terminated polybutadiene and mixtures thereof. 
     
     
       24. The process defined in claim 22, wherein the non-hydrophilic polyol is a polyether polyol. 
     
     
       25. The process defined in claim 24, wherein the polyether polyol has a molecular weight in the range of from about 200 to about 10,000. 
     
     
       26. The process defined in claim 15, wherein the isocyanate is represented by the general formula:   Q(NCO).sub.i     wherein i is an integer of two or more and Q is an organic radical having the valence of i.   
     
     
       27. The process defined in claim 15, wherein the isocyanate is selected from the group consisting of 1,6-hexamethylene diisocyanate, 1,4-butylene diisocyanate, furfurylidene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenylpropane diisocyanate, 4,4'-diphenyl-3,3'-dimethyl methane diisocyanate, 1,5-naphthalene diisocyanate, 1-methyl-2,4-diisocyanate-5-chlorobenzene, 2,4-diisocyanato-s-triazine, 1-methyl-2,4-diisocyanato cyclohexane, p-phenylene diisocyanate, m-phenylene diisocyanate, 1,4-naphthalene diisocyanate, dianisidine diisocyanate, bitoluene diisocyanate, 1,4-xylylene diisocyanate, 1,3-xylylene diisocyanate, bis-(4-isocyanatophenyl)methane, bis-(3-methyl-4-isocyanatophenyl)methane, polymethylene polyphenyl polyisocyanates and mixtures thereof. 
     
     
       28. The process defined in claim 15, wherein the isocyanate is selected from the group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and mixtures thereof. 
     
     
       29. The process defined in claim 15, wherein the isocyanate is selected from the group consisting of (i) 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate and mixtures thereof; and (ii) mixtures of (i) with an isocyanate selected from the group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and mixtures thereof. 
     
     
       30. The foamed isocyanate-based polymer defined in claim 1, wherein the active hydrogen-containing compound comprises an overall ethylene oxide content in the range of from about 35 to about 70 percent by weight. 
     
     
       31. The foamed isocyanate-based polymer defined in claim 1, wherein the active hydrogen-containing compound comprises an overall ethylene oxide content in the range of from about 50 to about 65 percent by weight. 
     
     
       32. The foamed isocyanate-based polymer defined in claim 1, wherein the active hydrogen-containing compound comprises a mixture of at least two active hydrogen-containing compounds, the mixture having the overall ethylene oxide content. 
     
     
       33. The foamed isocyanate-based polymer defined in claim 1, wherein the active hydrogen-containing compound is a mixture comprising an hydrophilic polyol and a non-hydrophilic polyol. 
     
     
       34. The foamed isocyanate-based polymer defined in claim 33, wherein the hydrophilic polyol is selected from the group consisting of diols, triols and tetrols, the hydrophilic polyol containing polyoxyalkylene groups, the polyoxyalkylene groups comprising at least 25 percent by weight of ethylene oxide. 
     
     
       35. The foamed isocyanate-based polymer defined in claim 33, wherein the hydrophilic polyol is selected from the group consisting of diols, triols and tetrols, the hydrophilic polyol containing polyoxyalkylene groups, the polyoxyalkylene groups comprising from about 40 to about 85 percent by weight of ethylene oxide. 
     
     
       36. The foamed isocyanate-based polymer defined in claim 33, wherein the hydrophilic polyol is selected from the group consisting of diols, triols and tetrols, the hydrophilic polyol containing polyoxyalkylene groups, the polyoxyalkylene groups comprising from about 55 to about 85 percent by weight of ethylene oxide. 
     
     
       37. A foamed isocyanate-based polymer having a cellular structure and containing a superabsorbent material, the polymer being capable of: (i) absorbing at least about 20 times its weight of water maintained at a temperature of from about 20° to about 25° C., and (ii) retaining at least about 20 times its weight of absorbed water which is bound to the superabsorbent material, the foamed isocyanate-based polymer being expanded from a reaction mixture comprising an isocyanate and an active hydrogen-containing compound having an overall ethylene oxide content in the range of from about 20 to about 70 percent by weight. 
     
     
       38. The foamed isocyanate-based polymer defined in claim 37, wherein the polymer is capable of: (i) absorbing from about 20 to about 100 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 20 to about 90 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       39. The foamed isocyanate-based polymer defined in claim 37, wherein the polymer is capable of: (i) absorbing from about 20 to about 80 times its weight of water maintained at a temperature of from about 20° C. to about 25° C. and (ii) retaining from about 20 to about 70 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       40. The foamed isocyanate-based polymer defined in claim 37, wherein the polymer is capable of: (i) absorbing from about 35 to about 65 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 30 to about 55 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       41. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is a synthetic polymer. 
     
     
       42. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is a cellulosic polymer. 
     
     
       43. The foamed isocyanate-based polymer defined in claim 42, wherein the cellulosic polymer is a carboxymethyl cellulose. 
     
     
       44. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is selected from a polymer of an acrylic monomer and a polymer of a vinyl monomer. 
     
     
       45. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is selected from the group consisting of polyvinylpyrrolidone, sulfonated polystyrene, polysulfethyl acrylate, poly(2-hydroxyethylacrylate), polyacrylamide, polyacrylic acid, poly(acrylic acid alkali metal salt), starch modified polyacrylic acid, poly(starch modified acrylic acid alkali metal salt), hydrolyzed polyacrylonitrile, poly(hydrolyzed polyacrylonitrile alkali metal salt) and mixtures thereof. 
     
     
       46. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is present in an amount up to about 150 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       47. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is present in the range of from about 20 to about 80 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       48. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is present in the range of from about 35 to about 75 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       49. The foamed isocyanate-based polymer defined in claim 37, wherein the superabsorbent material is present in the range of from about 55 to about 65 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the foamed isocyanate-based polymer. 
     
     
       50. The foamed isocyanate-based polymer defined in claim 37, wherein the active hydrogen-containing compound comprises an overall ethylene oxide content in the range of from about 35 to about 70 percent by weight. 
     
     
       51. The foamed isocyanate-based polymer defined in claim 37, wherein the active hydrogen-containing compound comprises an overall ethylene oxide content in the range of from about 50 to about 65 percent by weight. 
     
     
       52. The foamed isocyanate-based polymer defined in claim 37, wherein the active hydrogen-containing compound comprises a mixture of at least two active hydrogen-containing compounds, the mixture having the overall ethylene oxide content. 
     
     
       53. The foamed isocyanate-based polymer defined in claim 37, wherein the active hydrogen-containing compound is a mixture comprising an hydrophilic polyol and a non-hydrophilic polyol. 
     
     
       54. The foamed isocyanate-based polymer defined in claim 53, wherein the hydrophilic polyol is selected from the group consisting of diols, triols and tetrols, the hydrophilic polyol containing polyoxyalkylene groups, the polyoxyalkylene groups comprising at least 25 percent by weight of ethylene oxide. 
     
     
       55. The foamed isocyanate-based polymer defined in claim 53, wherein the hydrophilic polyol is selected from the group consisting of diols, triols and tetrols, the hydrophilic polyol containing polyoxyalkylene groups, the polyoxyalkylene groups comprising from about 40 to about 85 percent by weight of ethylene oxide. 
     
     
       56. A polyurethane foam having a cellular structure and containing a superabsorbent material, the foam being capable of: (i) absorbing at least about 20 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining at least about 20 times its weight of absorbed water which is bound to the superabsorbent material, the foam being expanded from a reaction mixture comprising an isocyanate and an active hydrogen-containing compound comprising a polyol having an overall ethylene oxide content in the range of from about 20 to about 70 percent by weight. 
     
     
       57. The polyurethane foam defined in claim 56, wherein the foam is capable of: (i) absorbing from about 20 to about 100 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 20 to about 90 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       58. The polyurethane foam defined in claim 56, wherein the foam is capable of: (i) absorbing from about 20 to about 80 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 20 to about 70 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       59. The polyurethane foam defined in claim 56, wherein the polymer is capable of: (i) absorbing from about 35 to about 65 times its weight of water maintained at a temperature of from about 20° C. to about 25° C., and (ii) retaining from about 30 to about 55 times its weight of absorbed water which is bound to the superabsorbent material. 
     
     
       60. The polyurethane foam defined in claim 56, wherein the superabsorbent material is a synthetic polymer. 
     
     
       61. The polyurethane foam defined in claim 56, wherein the superabsorbent material is a cellulosic polymer. 
     
     
       62. The polyurethane foam defined in claim 61, wherein the cellulosic polymer is a carboxymethyl cellulose. 
     
     
       63. The polyurethane foam defined in claim 56, wherein the superabsorbent material is selected from a polymer of an acrylic monomer and a polymer of a vinyl monomer. 
     
     
       64. The polyurethane foam defined in claim 56, wherein the superabsorbent material is selected from the group consisting of polyvinylpyrrolidone, sulfonated polystyrene, polysulfethyl acrylate, poly(2-hydroxyethylacrylate), polyacrylamide, polyacrylic acid, poly(acrylic acid alkali metal salt), starch modified polyacrylic acid, poly(starch modified acrylic acid alkali metal salt), hydrolyzed polyacrylonitrile, poly(hydrolyzed polyacrylonitrile alkali metal salt) and mixtures thereof. 
     
     
       65. The polyurethane foam defined in claim 56, wherein the superabsorbent material is present in an amount up to about 150 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the polyurethane foam. 
     
     
       66. The polyurethane foam defined in claim 56, wherein the superabsorbent material is present in the range of from about 20 to about 80 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the polyurethane foam. 
     
     
       67. The polyurethane foam defined in claim 56, wherein the superabsorbent material is present in the range of from about 35 to about 75 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the polyurethane foam. 
     
     
       68. The polyurethane foam defined in claim 56, wherein the superabsorbent material is present in the range of from about 55 to about 65 parts by weight per hundred parts by weight of active hydrogen-containing compound used to produce the polyurethane foam. 
     
     
       69. The polyurethane foam defined in claim 56, wherein the polyol has an overall ethylene oxide content in the range of from about 35 to about 70 percent by weight. 
     
     
       70. The polyurethane foam defined in claim 56, wherein the polyol has an overall ethylene oxide content in the range of from about 50 to about 65 percent by weight. 
     
     
       71. The polyurethane foam defined in claim 56, wherein the polyol comprises a mixture of at least two polyols, the mixture having the overall ethylene oxide content. 
     
     
       72. A personal hygiene device having a bodily fluid absorbent layer consisting essentially of the foamed isocyanate-based polymer defined in claim 1. 
     
     
       73. A personal hygiene device having a bodily fluid absorbent layer consisting essentially of the foamed polyurethane polymer defined in claim 14.